I've attached a very handy tool for simulating or calcuating the power deliver to a load via DAC output coupled to a transformer. Note, the assumption is the AD9957 is in single tone mode. In single tone mode, the DAC input is driven to its full scale range. In quadrature mode, the IQ input range and insertion loss through the modulator may not present the full scale range to the DAC input. So, using single tone mode power as the base line, you can better experiment where losses are coming from in the signal chain.

I've attached a very handy tool for simulating or calcuating the power deliver to a load via DAC output coupled to a transformer. Note, the assumption is the AD9957 is in single tone mode. In single tone mode, the DAC input is driven to its full scale range. In quadrature mode, the IQ input range and insertion loss through the modulator may not present the full scale range to the DAC input. So, using single tone mode power as the base line, you can better experiment where losses are coming from in the signal chain.